1. Field of the Invention
This invention relates to vibratory conveyors and, more particularly, to a conveyor with a spiral ramp for the vertical conveyance of materials.
2. Background Art
Vibratory conveyors utilizing a spiral ramp surface to elevate material are well known. Most commonly, a vibration generating structure is directly attached to a helical flight defining the ramp surface and imparts vibration thereto through brute force. Such a system is shown in U.S. Pat. No. 2,927,683, to Carrier. This and other like systems have several drawbacks.
First, the dynamic forces applied to the bearing surface for the apparatus are substantial, thereby generally precluding above grade installations.
An additional problem with the above-described prior art structures is that large motors are required to handle system start-up and shut-down. Even with large motors, premature wear on and/or failure of the motors and associated structure may result. This latter problem is aggravated in systems wherein the motors employ a fixed eccentric weight to develop vibratory forces upon rotation of the motor shaft.